LICENSE.txt: bump copyright year
test/index.html:

* remove unneeded type="text/javascript"
* specify charset="iso-8859-1" and lang="en"
jquery.mousewheel.js: keep the style consistent
ChangeLog.markdown: switch to h2 for the versions and use more Markdown syntax
README.markdown: use more Markdown syntax.

use the relative link to LICENSE.txt and break a very long line.
Add JSHint support.

Add package.json with check and lint commands to run jshint using .jshintrc.